A standard drill chuck has a chuck body having at its rear end a drive-spindle seat and in which jaws having gripping faces are movable in guide grooves extending at an acute angle to the chuck axis. The jaws engage by external teeth an internal screwthread of a threaded ring rotatable on the chuck body in order to move between an open position and a closed position, and an adjustment sleeve surrounding the chuck body is provided to actuate the threaded ring, and a cover disk at the rear end is formed with chip-discharge holes.
A problem encountered with drill chucks is that drill chips can penetrate into the housing—especially during overhead work—with the result that the action of drilling or adjusting the jaws can be impeded or the service life of the drilling machine can be reduced due to particles or drill chips inside the drill chuck that have an abrasive effect and increase wear.
In order to prevent this problem and extend the service life of the drill chuck in drill chucks of the above-referenced type, such as those disclosed for example in U.S. Pat. No. 6,581,942, the particles that have already penetrated into the drill chuck can be forced out through chip-discharge holes in the cover disk. In the drill chucks known in the art, however, this occurs unpredictably or randomly, and thus not effectively.